Topographic And Geomorphologic Features And Analyses Of The Seafloor And Seamounts In The Yap Seamounts Area

In this paper, we describe the geomorphologic features of the seafloor in the Yap seamounts area through the high-resolution topographic data measured by multi-beam sounding system. Comprehensively analyze the cause of the terrain in the studied area combined with the existing data and predecessors’ studying results. The Caroline Ridge formed because of the effect of hot pot and magma overflow. Under the effect of the slab pull force due to the northern subduction of Pacific plate, the Sorol Trough, which is in the middle part of the ridge, separates the Caroline Ridge into two parts, the northern part and southern part, and the trough separates the Pacific plate and the Caroline plate at the meantime. Due to the change in the direction of plate motion, the motion of the Pacific Plate changes from subduction into squeezing movement along the Yap Trench, and the Caroline Plate continues to dip down the Yap Trench. Because of the differences between the plate tectonic movements, the trend of Yap Trench changes at the central. The slab in the southern part of the trench dipping deeper down, so that the igneous activity under the southern back-arc basin is more active, there are more seamounts in the basin.Shape statistics have been compiled from the profiles of seamounts in the Yap area by the seafloor topographic data. On each profile a maximum height, a summit diameter, a basal diameter, a slope angle, a flatness, are measured. According to the distribution of seamounts, we divide these seamounts into different groups. Analyze the relationships among these seamount morphological parameters in different area respectively, and compare the results. Summit height increases with basal diameter, the higher the seamount is the linear relationship between them is more obvious, but there is no relationship between summit diameter and height. Flatness of seamounts is small in both seamounts area, and there is no obvious relationship between flatness and summit height. In the Sorol-Caroline seamounts area, there is an obvious classification feature among the flatness figures, the dispersion of the two sets of data are small. Compared with the Yap back-arc seamounts area, the morphological variation of seamounts in the Sorol-Caroline seamounts area is more complicated, this is probably because of the geology environment in Sorol-Caroline seamounts area is more complicated. Slope angles of the seamounts vary around a special number, the higher the summit height is the closer the number. This situation has nothing to do with the seamounts area and geology environment.